AB1422 CLINICAL MANIFESTATIONS AT THE ONSET OF PEDIATRIC MIXED CONNECTIVE TISSUE DISEASE (PMCTD): A SYSTEMATIC REVIEW.
Authors: A. Terminiello, E. Marrani, I. Pagnini, I. Maccora, M. V. Mastrolia, A. Alletto, G. Simonini
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> pMCTD is a rare disorder that includes features of systemic lupus erythematosus, polymyositis/dermatomyositis, juvenile idiopathic arthritis, and systemic sclerosis. Fifty years have passed since Sharp identified MCTD in 1972, and diagnosis of this disorder remains challenging. <h3>Objectives</h3> The aim of this review is to identify any clinical features at the diagnosis of pMCTD and manifestations that are not currently part of the available diagnostic criteria. <h3>Methods</h3> A systematic literature review was performed in accordance with PRISMA guidelines using electronic bibliographic databases: MEDLINE via PubMed and EMBASE. Data obtained were extracted using a dedicated database containing clinical data that best categorize patient characteristics. Criteria for inclusion: studies including patients with a pMCTD diagnosis with onset before 18 years of age and reporting a description of initial clinical features. <h3>Results</h3> The search returned a total of 1372 results: 409 articles were excluded as duplicates and 790 based on title/abstract, 133 because of publication type (n = 4) or because the full text was not available (n = 65) or not in English (n = 64). One (n=1) eligible article resulted from manual screening of references cited in the selected publications and in the reviews. Finally, 41 articles were included: 23 case reports, 9 case series, 5 prospective, and 4 retrospective studies from 1973 to 2019, with a total number of 218 patients. They were predominantly female (81.56%, n=167), and the mean age at onset was 147 months (median 126 months, 10.5 years). When indicated, the most commonly used criteria for diagnosis were Kasukawa criteria (50%, 11 studies), then Alarcon-Segovia criteria (31%, 7 studies), then Sharp criteria (23%, 5 studies); no Khan criteria were used. Clinical features are listed in Figure 1. Joint involvement, Raynaud's phenomenon, myositis, and swollen fingers/hands are the most common clinical features at diagnosis according to the data reported in the literature, although with slightly lower percentages than in other reviews. Dermatologic signs are very heterogeneous, but were found to be a very present feature at disease onset, affecting 1/3 of patients. Fever, not covered by any of the diagnostic criteria, was noted in 1/4 of cases. Pulmonary and esophageal involvement are reported in a lower percentage at the onset of the disease, indicating a more developmental nature of these conditions. <h3>Conclusion</h3> The data from this systematic review suggest greater clinical heterogeneity of the disease in the pediatric population, for which there are no validated diagnostic criteria. Typical features appear to be less common when case reports are included, suggesting a less characteristic initial presentation than an advanced stage; therefore, the absence of typical features at baseline should not preclude a diagnosis of pMCTD. Fever often occurs early in the disease and is not included in the diagnostic criteria. This systematic review may provide useful insights for future research to better assess the clinical features of pMCTD and the potential development of scores/algorithms for diagnosis in the pediatric population. <h3>References</h3> [1] Sharp GC, Irvin WS, Tan EM, Gould RG, Holman HR (1972) Mixed connective tissue disease–an apparently distinct rheumatic disease syndrome associated with a specific antibody to an extractable nuclear antigen (ENA). Am J Med 52(2):148–159 [2] Singsen BH, Swanson VL, Kornreich HK, et al. Mixed connective tissue disease in childhood: a clinical and serologic survey. J Pediatr 1977;90:893– 900. [3] Fraga A, Gudino J, Ramos-Niembro F, et al. Mixed connective tissue disease in childhood. Am J Dis Child 1978;132:263– 5. [4] Kahn MF, Appelboom T. In: Kahn MF, Peltier AP, Meyer O, editors. Les Maladies Systemiques. Paris: Flammarion; 1991. p. 545–56. [5] Sharp GC, Kasukawa R, Alarcon-Segovia D, Villarreal M. In: Kasukawa R, Sharp GC, editors. Mixed connective tissue diseases and anti-nuclear antibodies. Amsterdam: Excerpta Medica; 1987. p. 23–48. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.